Paver Calculator: Pavers, Base Gravel and Polymeric Sand
Patio size and paver size in, and it returns the paver count, the gravel base in cubic yards and tons, the bedding sand, the polymeric sand and the feet of edge restraint. The base is the line most people get wrong, and it is usually the largest thing on the truck.
When the figures look right, the paver material list downloads as a real PDF with your business details on it, built inside your own browser. Nothing you type is uploaded anywhere.
Worked example
These are the figures the calculator opens with and the answer it gives. Change anything above and every number below moves with it.
- Patio length20 ft
- Patio width12 ft
- Paver length8 in
- Paver width4 in
- Paver thickness2.375 in
- Joint width0.0625 in
- Compacted gravel base6 in
- Bedding sand1 in
- Waste allowance10 %
Pavers to buy1,161 pavers
| Patio area | 240 sq ft |
|---|---|
| One paver covers | 0.227 sq ftface plus one joint |
| Pavers per sq ft | 4.4 |
| Pavers before waste | 1,056 |
| Base gravel, compacted | 4.44 cu yd |
| Base gravel to order | 5.33 cu yd20% added for compaction |
| Base gravel weight | 7.47 tons |
| Bedding sand | 0.74 cu yd2,000 lb |
| Polymeric sand, 50 lb bags | 380 sq ft per bag |
| Edge restraint | 64 ft |
The material list this produces
| Pavers | 1,161 |
|---|---|
| Base gravel, cu yd | 5 |
| Bedding sand, cu yd | 1 |
| Polymeric sand, 50 lb bags | 3 |
| Edge restraint, ft | 64 |
| Edging spikes | 64 |
| Geotextile fabric, sq ft | 264 |
What this calculator assumes
- The joint default is 1/16 of an inch because concrete pavers are cast with spacer nubs on the sides and that is the joint you get when they are set tight. A hand set joint at 1/8 or wider takes noticeably more polymeric sand, so type the joint you are actually laying.
- Waste is 5 percent for a running bond laid square to the edges, 10 for most patios, and 15 or more for herringbone or a circle kit, because every angled cut throws away most of a paver.
- Base gravel is quoted compacted. Crushed stone loses about a fifth of its loose volume under a plate compactor, so the order line adds 20 percent back.
- Four inches of compacted base suits a foot traffic patio on good soil. Six is the common default, and eight to twelve is driveway and heavy clay territory.
- Polymeric sand is the volume of the joints at the full thickness of the paver, at about 100 pounds per cubic foot.
- Weights use 2,800 lb per cubic yard for crushed stone and 2,700 for bedding sand.
The paver count comes from the joint, not the catalog
A 4 by 8 paver is sold as covering 4.5 to the square foot, and it would, if the pavers touched. They do not. Every paver sits inside a cell of its own face plus one joint, so the real figure at a 1/16 inch joint is 4.4 per square foot, and at 1/8 it drops to 4.3.
On a 20 by 12 patio that is 1,161 pavers against 1,135, a difference of 26. That is small, but it runs the other way from the direction people guess, and the catalog number leaves you short rather than long.
Large format is where it shows up properly. The same 240 square feet in 12 by 12 pavers is 262 pieces, and in 6 by 6 it is 1,035. Type the actual face size of what you are buying rather than the nominal name on the pallet tag.
The base is most of the order and all of the failure
Six inches of compacted gravel under a 240 square foot patio is 4.44 cubic yards in place. Crushed stone loses about a fifth of its loose volume under a plate compactor, so the order is 5.33 cubic yards, which is 7.47 tons and more than one delivery on a small truck.
Four inches is enough for a foot traffic patio on ground that drains. Six is the default because most ground is not that. Eight to twelve is what a driveway or heavy clay wants, and the calculator warns rather than silently accepting anything under four.
Base gets compacted in lifts of three or four inches, not in one pass. A twelve inch base rolled in one go is a twelve inch base that settles, and settled pavers are a rebuild rather than a repair.
Polymeric sand is sold by coverage and bought by joint volume
Bag coverage charts assume a joint. Change the joint and the coverage changes with it, because the sand is filling a volume rather than a surface. That 20 by 12 patio takes 3 bags at a 1/16 inch joint and 5 at 1/8, from exactly the same paver count.
The default here is 1/16 because concrete pavers are cast with spacer nubs on their sides, and set tight that is the joint you get. A hand set joint, a tumbled paver with a rounded edge, or a flagstone pattern all open up and all take more.
Sweep it in dry, blow the faces clean before you wet it, and wet it the way the bag says. Polymeric sand left on the surface hazes, and it is far easier to keep it off than to get it off.
Edge restraint is not optional and it is easy to leave off
That same patio needs 64 feet of edge restraint, one lap of the perimeter, plus a spike about every foot. Without it the outer course creeps outward under traffic, the joints open, the sand washes and the field starts to move.
Restraint goes on the compacted base and beyond the paver edge, not on the bedding sand. Setting it on the sand is the single most common installation fault, because the sand moves and takes the restraint with it.
Geotextile under the base is on the list at 10 percent over the area. It is not structural, it keeps the subgrade from pumping up into the stone, and on clay it is the difference between a base that lasts and one that turns to mud.
Questions people ask
How many pavers do I need for a 12 by 20 patio?
About 1,161 pavers of 4 by 8 with a 1/16 inch joint and 10 percent waste. The bare count is 1,056. The same patio is 262 pieces in 12 by 12.
How much gravel do I need under pavers?
Six inches compacted under a 12 by 20 foot patio, 240 square feet, works out to 4.44 cubic yards in place, so order 5.33 to allow for compaction, which is about 7.47 tons.
Landscaping estimate template and Landscaping invoice template, free, no signup, PDF Word and Excel.
Common sizes, worked out
The same calculator with the numbers already filled in, one page per size, each ending in its own material list.
More sizes, answered
Each row is this calculator run with those numbers when the page was built. Type the same numbers in above to see every line of the working.
| Example | What it assumes | Pavers to buy |
|---|---|---|
| 7x7 patio | 49 sq ft of patio, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 237 pavers |
| 8x8 patio | 64 sq ft of patio, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 310 pavers |
| 10x10 patio | 100 sq ft of patio, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 484 pavers |
| 10x12 patio | 120 sq ft of patio, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 581 pavers |
| 8x16 patio | 128 sq ft of patio, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 620 pavers |
| 200 sq ft | 200 sq ft of patio, typed 10 by 20, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 968 pavers |
| 15x15 patio | 225 sq ft of patio, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 1,089 pavers |
| 300 sq ft | 300 sq ft of patio, typed 20 by 15, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 1,451 pavers |
| 20x20 patio | 400 sq ft of patio, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 1,935 pavers |
| 600 sq ft | 600 sq ft of patio, typed 20 by 30, 4 by 8 in pavers, 6 in compacted base, 1 in bedding sand, ten percent waste. | 2,902 pavers |